Speaker system for picture receiver and speaker installing method

ABSTRACT

A speaker system for a picture receiver provides for lessening of the casing width of the picture receiver while assuring highly uniform acoustic characteristic at listening points in a sufficiently broad range. The speaker system for picture receiver and its speaker installing method comprises a first speaker for reproducing medium and high range sound at the right and left of the screen of a picture receiver and a second speaker for reproducing medium and low range sound under the screen, wherein the speaker system is set in such place that when a listening point is set at a position a first distance apart from the picture receiver and within a second distance from the front axis at the center of the right and left of the screen, the distance from the first speaker to the listening point is R 1 , the distance from the second speaker to the listening point is R 2 , and the crossover frequency is f, then R 1 , R 2  and f satisfy the specified relative formula.

This application is a U.S. National Phase Application of PCTInternational Application PCT/JP2004/011666.

TECHNICAL FIELD

The present invention relates to a speaker system used for picturereceiver and a speaker installing method.

BACKGROUND ART

A conventional speaker system for picture receiver comprises a speakerfor reproducing medium and high range sound at the sides of the screenof a picture receiver and a speaker for reproducing medium and lowrainge sound under the screen of the receiver. Such a conventionalspeaker system for picture receiver is disclosed, for example, inJapanese Laid-Open Patent 2000-354285 (page 1 to 5, FIG. 1).

FIG. 4 shows a conventional speaker system for picture receiver. Thespeaker system for picture receiver of FIG. 4 comprises speaker 102 forreproducing medium and high range sound at the sides of screen 101 of apicture receiver, speaker 103 for reproducing medium and low raingesound under the screen 101, and dividing network 104. In thisconfiguration, the volume difference between speaker 102 for medium andhigh range sound and speaker 103 for medium and low range sound isadjusted so that the acoustic characteristic becomes nearly uniform at alistening point on the front axis at the center of the right and left.

And, for assuring the uniform acoustic characteristic also at alistening point apart from the front axis at the center of the right andleft, it is a common method that the cut-off frequencies of the speakerfor medium and high range sound and the speaker for low range sound arelowered as much as possible or the positions of the speaker for mediumand high range sound and the speaker for medium and low range sound areapproached as much as possible.

DISCLOSURE OF THE INVENTION

A speaker system for picture receiver, comprising:

a first speaker for reproducing medium and high range sound which form asound image nearly at the vertical center in the right and left regionof the screen of a picture receiver; and

a second speaker for reproducing medium and low range sound under thescreen,

wherein when a listening point is set at a point a first distance apartin forward direction of the screen and within a second distance from thefront axis at the center of the right and the left of the screen,distance R1 from the sound source position of the first speaker to thelistening point, distance R2 from the sound source position of thesecond speaker to the listening point, and crossover frequency f of thefirst speaker and the second speaker frequency-divided by dividingnetwork satisfy the following relative equation:|exp(−j×k×R1)×exp(j×D×π/4)+(−1)^(D+1)×exp(−j×k×R2)×exp(−j×D×π/4)|≧1/√{squareroot over (2)},k=2π×f/c,

-   -   exp=exponential function,    -   j=unit of complex number,    -   c=sound velocity,    -   π=circular constant,    -   D=degree of dividing network (0 or positive integers).

A speaker installing method of installing a speaker system for picturereceiver comprising:

a first speaker for reproducing medium and high range sound which form asound image nearly at the vertical center in the right and left regionof the screen of a picture receiver, and

a second speaker for reproducing medium and low range sound under thescreen,

wherein the first speaker and the second speaker are installed in suchplace that when a listening point is set at a point a first distanceapart in forward direction of the screen and within a second distancefrom the front axis at the center of the right and the left of thescreen, distance R1 from the sound source position of the first speakerto the listening point, distance R2 from the sound source position ofthe second speaker to the listening point, and crossover frequency f ofthe first speaker and the second speaker frequency-divided by dividingnetwork satisfy the following relative equation:|exp(−j×k×R1)×exp(j×D×π/4)+(−1)^(D+1)×exp(−j×k×R2)×exp(−j×D×π/4)|≧1/√{squareroot over (2)},

-   -   k=2π×f/c,    -   exp=exponential function,    -   j=unit of complex number,    -   c=sound velocity,    -   π=circular constant,    -   D=degree of dividing network (0 or positive integers).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a speaker system in one preferredembodiment of the present invention.

FIG. 2 is a sound pressure distribution diagram of an audio-visual area,supposing that the screen size is 37 inches in FIG. 1.

FIG. 3 is a sound pressure distribution diagram of an audio-visual area,supposing that the screen size is 50 inches in FIG. 1.

FIG. 4 is a block diagram of a conventional speaker system.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

However, in the conventional configuration, the acoustic characteristicis uniform at a listening point on the front axis at the center of theright and the left, but in case the frequency of the dividing network istoo high, the range of service area that can be provided with theacoustic characteristic is not clear. Accordingly, there is no othermethod than actually setting up the system each time and checking it bythe auditory sense.

Actually, for the purpose of setting a relatively wide service areabefore making the system, as described above, a method generallyemployed is such that a frequency lower than 200 Hz having nodirectivity is used as the cut-off frequency of a speaker for medium andhigh range sound and a speaker for low range sound, or the positions ofthe speaker for medium and high range sound and the speaker for mediumand low range sound are arranged as much closer to each other aspossible. However, if the cut-off frequency is set lower, it will becomenecessary to use large-sized speakers for medium and high range sound atthe sides of the picture receiver. Also, if the speaker for low-pitchedsound is approached to the speaker for medium and high range soundlocated at the sides of the picture receiver, a large space will becomenecessary as a place for installing both speakers.

Since a sound image is formed at a position close to the speaker formedium and high range sound having high sensitivity because of the humanauditory sense, it is desirable to install the speaker for medium andhigh range sound at the vertical center of the screen in order to formthe sound image at a position close to the center of the screen.However, in the above configuration, a large space is required forinstalling a speaker for medium and high range sound. Therefore, itbecomes very difficult to lessen the casing width of the picturereceiver.

The present invention is intended to solve the conventional problem, andthe object is to obtain the relationship between the optimum speakerposition in a specified audio-visual area and the frequency of dividingnetwork in order that the positions of a speaker for medium and highrange sound and a speaker for medium and low range sound and the cut-offfrequency satisfy the relative equation, thereby making it easy todecide each element. Also, even when the cut-off frequency is set to anincredibly high value, it is possible to decide each element so thathighly uniform acoustic characteristic can be assured at listeningpoints in a sufficiently broad range. Also, even when a speaker formedium and high sound and a speaker for medium and low sound are spacedincredibly apart from each other, it is possible to determine eachelement so that highly uniform acoustic characteristic can be assured atlistening points within a broad range.

The preferred embodiments of the present invention will be described inthe following with reference to the drawings.

(Preferred Embodiment 1)

FIG. 1 is a diagram showing the configuration of a speaker system forpicture receiver in the preferred embodiment 1 of the present invention.In FIG. 1, mid-high range speaker 2 is installed nearly at the verticalcenter of screen 1 in the right and left region of screen 1 of a picturereceiver, and mid-low range speaker 3 is installed under the screen 1.In this configuration, since only the mid-high range speaker smaller insize is installed at the right and left of screen 1 while forming asound image nearly at the center of the screen, it is possible to lessenthe casing width of the picture receiver.

Dividing network 4 serves to divide the audio frequency range generatedfrom mid-high range speaker 2 and the audio frequency range generatedfrom mid-low range speaker 3, and therefore, it usually comprises ahigh-pass filter and a low-pass filter. The cut-off characteristiccrossing frequency of each filter is called crossover frequency. Thecrossover frequency is adjusted in accordance with the characteristic ofthe speaker used. Here, if intended to reduce the size of mid-high rangespeaker 2, it is necessary to set the crossover frequency higher.Generally, if it is possible to set the crossover frequency higher than200 Hz, a sufficiently small-sized speaker can be used and it willgreatly save the space.

Next, listening point M is set at a position a first distance apart fromscreen 1 in the forward direction (Z-axis direction in FIG. 1) of thescreen from the picture receiver. Presently, there is an increasingtrend of extra-fine and high-quality pictures, and wider screens withaspect ratio of 16:9. Accordingly, the speaker system must be set inanticipation of such tendency that the audience may enjoy reallyimpressive pictures from near a wide screen displaying extra-fine andhigh-quality pictures. Because of such background, as the firstdistance, for example, being a distance three times the vertical size ofscreen 1, listening point M is set at a position spaced apart by thisdistance. Next, listening point N is set at a position a second distanceapart from the front axis (Z axis in FIG. 1) at the center of the rightand left of screen 1. As the second distance, for example, it is set to1 m. This distance is set in anticipation of such situations that theaudience includes a plurality of persons and that the audience moveswhile watching the pictures.

Since a common-type large television set is anticipated in setting thesecond distance, it is preferable to set the distance in accordance withthe type of picture receiver. Also, it is possible to set the seconddistance to a value different from the above depending upon the picturequality, sound quality, and type of picture receiver.

Further, in the speaker system of the present invention, the right andleft positions (positions in the X-axis direction in FIG. 1) of mid-lowrange speakers 3 are determined as follows.

First, the distance between mid-high range speaker 2 and listening pointN is R1. Similarly, the distance between mid-low range speaker 3 andlistening point N is R2. When the crossover frequency is f and thedegree of dividing network is D as described above, the speaker isdesigned and each speaker is installed so that the formula such as|exp(−j×k×R1)×exp(j×D×π/4)+(−1)^(D+1)×exp(−j×k×R2)×exp(−j×D×π/4)|≧1/√{squareroot over (2)}  (formula 1)k=2π×f/c  (formula 2)is satisfied. For example, the value of R2 is decided by using R1 thatis decided nearly in single meaning with the size of screen 1 decided,and f of which the optimum value is decided by the characteristic of thespeaker used. Since the formula 1 is inequality, R2 is represented as avalue having a specific range.

Next, under the structural limit of configuration, the portion where amid-low range speaker can be installed in the lower region of screen 1is decided. For example, in the case of a television set using acathode-ray tube, it cannot be installed on a portion where a column isdisposed to support a heavy cathode-ray tube. Or, it cannot be installedon a portion where a remote control receiver or operation button or thelike is disposed. And with the installing portion decided, mid-low rangespeaker 3 is installed thereon in a position where R2 is satisfied.

The operation of a speaker system having the above configuration will bedescribed in the following.

First, mid-high range speaker 2 and mid-low range speaker 3 are adjustedso that the acoustic characteristic becomes uniform at listening point Mwith respect to the volume difference at the audible frequency. In thisway, the uniformity of acoustic characteristic at listening point M canbe assured.

However, the uniformity of acoustic characteristic cannot be assured atpoints other than the listening point that is the reference point forthe adjustment. This is because when a sound of same frequency isgenerated from different sound sources, if the distance from each soundsource to the listening point is changed, it will cause the generationof attenuation due to phase difference as the difference in distanceturns into difference in sound wave phase. When the frequency is low orhigh enough, the sound is produced from only one of the speakers due todividing network 4, and there arises no such problem. However, in thevicinity of the crossover frequency, the problem is remarkable becausethe sound is produced from both of the speakers.

In order to solve this problem, in the range where it is anticipatedthat the audience hears the attenuation at the crossover frequency, incase the attenuation is 0 dB without depending upon distance on thecentral axis of two speakers, it is preferable to be kept within −3 dB.Attenuation of −3 dB means that the sound is attenuated to half theenergy of original sound. Generally, the human auditory sense is able tosense incongruity when the energy of sound becomes lower than half theenergy of original sound. From this point of view, it can be judged thatthe uniformity of acoustic characteristic can be obtained when theattenuation is about −3 dB in actual use.

Here, the background and meaning of establishing (formula 1) will bebriefly described in the following.

In (formula 1), k×R1 of exp(−j×k×R1) corresponds to the value ofdistance from mid-high range speaker 2 to listening point N representedby sound wave phase, taking into account the relation of (formula 2).Accordingly, exp(−j×k×R1) of formula 1 is a phase lag generated beforethe sound of frequency f produced from mid-high range speaker 2 reachesthe listening point N.

Incidentally, dividing network 4 is inserted between the output circuitof audio signal and mid-high range speaker 2, and the audio signal isfed to mid-high range speaker 2 via dividing network 4.

Dividing network 4 serves to separate the audio signal fed to mid-highrange speaker 2 from the audio signal fed to mid-low range speaker 3 onthe frequency axis. Generally, a high-pass filter of D degree and alow-pass filter of D degree are formed through dividing network 4. Thesystem of mid-high range speaker 2 comprises a high-pass filter of Ddegree, and the system of mid-low speaker 3 comprises a low-pass filter.“D” is 0 or positive integers. Usually, mid-high range speaker 2 andmid-low range speaker 3 are considered to be pure resistance, and theoutput impedance of audio signal output circuit can be considered to bepure resistance of small value. There exist a circuit for mid-high rangespeaker 2 and a circuit for mid-low range speaker 3 in dividing network4. When “D” is 1, the circuit for mid-high range speaker 2 is formed ofa capacitor inserted in series fashion to mid-high range speaker 2, andthe circuit for mid-low range speaker 3 is formed of an inductorinserted in series fashion to mid-low range speaker 3. That is, thesystem of mid-high range speaker 2 is equivalent to a 1st-order advancecircuit in the vicinity of cut-off frequency, and the system of mid-lowrange speaker 3 is equivalent to a 1st-order lag circuit in the vicinityof cut-off frequency. Generally, the cut-off frequency of mid-high rangespeaker 2 and the cut-off frequency of mid-low range speaker 3 are setat same level. The cut-off frequency corresponds to crossover frequencyf.

Incidentally, since there exists dividing network 4 between the outputcircuit of audio signal and mid-high range speaker 2, the sound producedfrom mid-high range speaker 2 has a first order phase lead at crossoverfrequency f. That is, the phase leads by π/4 phase. Exp(j×π/4) of(formula 1) represents this phase lead.

Consequently, when the sound produced from mid-high range speaker 2reaches the listening point N, the phase shift is the product ofexp(−j×k×R1) and exp(j×π/4). That is, it corresponds toexp(−j×k×R1)×exp(j×π/4) in (formula 1).

On the other hand, taking into account the relation of (formula 2), k×R2of exp(−j×k×R2) of (formula 1) corresponds to the value of sound wavephase that represents the distance from mid-low range speaker 3 to thelistening point N. Accordingly, exp(−j×k×R2) of formula 1 is a phase laggenerated before the sound of frequency f produced from mid-low rangespeaker 3 reaches the listening point N.

There exists dividing network 4 between the output circuit of audiosignal and mid-low range speaker 3. When degree “D” is supposed to be 1,the sound produced from mid-low range speaker 3 has a first order phaselag at crossover frequency f. That is, the phase lags by π/4.Exp(−j×π/4) of (formula 1) represents this phase lag.

Consequently, when the sound produced from mid-low range speaker 3reaches the listening point N, the phase shift is the product ofexp(−j×k×R2) and exp(−j×π/4). That is, it corresponds toexp(−j×k×R2)×exp(−j×π/4) in (formula 1).

Incidentally, the sound at listening point N is the sound obtained whenthe sound that is produced from mid-high range speaker 2 and reaches thelistening point N is synthesized with the sound that is produced frommid-low range speaker 3 and reaches the listening point N. That is, thesynthesized sound reaching the listening point N can be represented by(formula 3).exp(−j×k×R1)×exp(j×π/4)+exp(−j×k×R2)×exp(−j×π/4)  (formula 3)

Since the amplitude of sound reaching the listening point N correspondsto the absolute value of (formula 3), the amplitude of sound reachingthe listening point N can be represented by (formula 4).|exp(−j×k×R1)×exp(j×π/4)−exp(−j×k×R2)×exp(−j×π/4)|  (formula 4)

Formula 4 supposes that the value of degree “D” is 1. In the presentinvention, degree “D” is not limited to 1. When the degree is 0 orvariable “D” as positive integer, since there exists dividing network 4of degree “D” between the output circuit of audio signal and mid-highrange speaker 2, the sound produced from mid-high range speaker 2 has aD order phase lead at crossover frequency f. That is, the phase leads byD×π/4. Since there exists dividing network 4 of degree “D” between theoutput circuit of audio signal and mid-low range speaker 3, the soundproduced from mid-low range speaker 3 has a D order phase lag atcrossover frequency f. That is, the phase lags by D×π/4. Accordingly,when the order is “D”, (formula 4) becomes (formula 5). In the case ofeven number, exp(j×π/4) and exp(−j×π/4) are reversed in phase, andtherefore, (formula 4) holds good taking into account the case of evennumber.|exp(−j×k×R1)×exp(j×D×π/4)+exp(−j×k×R2)×exp(−j×D×π/4)|  (formula 5)

Formula 5 is the left side of (formula 1), and the right side of(formula 1) represents −3 dB in the form of fractions.

As described above, the speaker system satisfies the formula 1, therebyassuring the uniformity of acoustic characteristic within −3 dB.

And, the uniformity of acoustic characteristic can be assured betweenlistening point M and listening point N. At positions going away fromlistening point M with respect to screen 1, the uniformity of acousticcharacteristic is assured because the difference between the distancesfrom the two sound sources is reduced. Thus, due to the configuration ofthe present invention, it is possible to realize an audio-visual areanecessary for regeneration of highly uniform acoustic characteristic inaccordance with the screen size of a picture receiver.

Next, in FIG. 2, the sound pressure distribution in 16:9 display of 37inch configured on the basis of (formula 1) is simulated by computer.The size is supposed to be the largest of all in display using CRT. Thelarger the screen, the sound source position is more remote and itbecomes more difficult to assure the uniformity of acousticcharacteristic.

In this simulation, crossover frequency f is first set to 500 Hz. Thisfrequency is more advantageous in such point that a smaller speaker isused, but the value is disadvantageous for assuring the uniformity ofacoustic characteristic.

Further, same as the relation of FIG. 1, the origin is set at the centerof screen 1 of a picture receiver. And, mid-high range speaker 2 isarranged at a position 0.455 meters in X-axis direction and 0 meter inY-axis direction. Also, mid-low range speaker 3 is arranged at aposition 0.22 meter in X-axis direction and 0.3 meter in Y-axisdirection corresponding to the position of R2 that satisfies (formula1).

The results of simulation under the above conditions are shown by aplurality of lines in FIG. 2. Horizontal axis 51 of the graph is thedistance in X-axis direction from the origin set at the center of screen1, and vertical axis 52 is the distance going away in forward directionfrom the screen. The whole plane corresponds to a view from aboveaudio-visual area 5 in FIG. 1. Also, each oblique line shows the line ofpoint of attenuation 1 dB each from the front axis at the center ofscreen 1 of the picture receiver at the set frequency. Particularly, thelines of attenuation 3 dB are shown by solid lines 53, 54, and theothers are shown by dotted lines.

It is clear that the more going outside the graph, the more the soundpressure is uniformly attenuated. Thus, since the screen height of thepicture receiver is 0.46 meters, listening point M is at the position of1.38 meters, showing that the position of 1 meter in the X-axisdirection therefrom corresponds to the line of sound pressure (−3 dB) ofabout √{square root over (½)}. Also, it shows that the region ofattenuation of within 3 dB is sufficiently assured.

Similarly, in FIG. 3, the sound pressure distribution in audio-visualarea 5 in 16:9 display of 50 inch is simulated by computer. The size issupposed to be that of display using PDP, and the screen is larger thanthe one shown in FIG. 2, and further, it is difficult to assure theuniformity of acoustic characteristic.

In this case, mid-high range speaker 2 is arranged at a position 0.615meter in X-axis direction and 0 meter in Y-axis direction from thecenter of screen 1 of the picture receiver. As a position correspondingto R2 that satisfies (formula 1), mid-low range speaker 3 is arranged ata position 0.25 meter in X-axis direction and −0.385 meter in Y-axisdirection from the center of screen 1 of the picture receiver. Crossoverfrequency f is 500 Hz the same as in FIG. 2.

Under the condition of FIG. 3, the same as in FIG. 2, the more goingoutside the graph, the more the sound pressure is uniformly attenuated.Each oblique line shows the line of point of point of attenuation 1 dBeach from the front axis at the center of screen 1 of the picturereceiver at the set frequency. Particularly, the lines of attenuation 3dB are shown by solid lines 57, 58, and the others are shown by dottedlines. Since the screen height of the picture receiver is 0.622 meter,listening point M is at the position of 1.866 meters in the direction ofvertical axis 56, showing that the position of 1 meter in the X-axis(horizontal axis 55) direction therefrom corresponds to the line ofsound pressure (−3 dB) of about √{square root over (½)}. Also, it showsthat the region of attenuation of within 3 dB is sufficiently assuredthe same as in FIG. 2.

As described above, arranging only a small-sized mid-high range speakernearly at the vertical center of the screen in the right and left regionof the screen of the picture receiver, it is possible to lessen thecasing width of the picture receiver as much as possible while formingthe sound image in the vicinity of the screen. As is obvious from theresult of simulation, setting f, R1, R2 and D in such relations that(formula 1) is satisfied, it is possible to realize an audio-visual areanecessary for the regeneration of highly uniform acoustic characteristicin accordance with the screen size of the picture receiver.

In the preferred embodiment of the present invention, the case ofsetting R2 that satisfies the relative formula from f and R1 has beendescribed. It is also preferable to set R1 and R2 beforehand providedthat the relative formula is satisfied and to set the dividing networkby obtaining, from the relative formula, crossover frequency f thatrealizes an audio-visual area for regeneration of highly uniformacoustic characteristic in such positional relations.

Also, described above is such a case that mid-high range speaker 2 isformed of a single speaker, but it is also preferable to arrange two ormore speakers in the right and left region of the screen of the picturereceiver so that the overall sound image is positioned nearly at thevertical center of the screen. In this case, it is defined that thefirst speakers for reproducing medium and high range sound comprise twoor more speakers.

Also, one example of the present invention shown in FIG. 2 and FIG. 3refers to mid-high range speaker and mid-low range speaker located atthe normal position in X-axis direction in FIG. 1, but naturally whenthe speaker system is arranged in a stereophonic fashion, the speakersystem of the present invention can be applied to both of the right andleft speaker systems.

As is obvious in the above description, the speaker system for picturereceiver and the speaker installing method of the present invention areable to lessen the casing width of the picture receiver while realizingan audio-visual area necessary for regeneration of high uniform acousticcharacteristic in accordance with the screen size of the picturereceiver.

Also, since the audio-visual area can be previously calculated from therelations of the speaker position and the dividing network frequency, itis possible to lessen the casing width of the picture receiver as muchas possible while realizing a minimum necessary audio-visual area inaccordance with the screen size of the picture receiver.

In this preferred embodiment, the crossover frequency is 500 Hz in thedescription, but nearly same effect can be obtained with the crossoverfrequency set to 400 Hz, 600 Hz or the like. In the case of a speakercapable of reproducing 200 Hz or over, the casing width required is 40mm at least. However, in the case of a speaker capable of reproducingonly 400 Hz or over, the width can be decreased to 20 mm at least.Accordingly, setting the crossover frequency to 400 Hz to 600 Hz, thesize of mid-high range speaker can be lessened and highly uniformacoustic characteristic can be assured at listening points in asufficiently broad range, and also, the casing width of the picturereceiver can be lessened. Thus, it is possible to enhance the freedom ofdesign.

INDUSTRIAL APPLICABILITY

The speaker system for picture receiver and the speaker installingmethod of the present invention are able to lessen the casing width ofthe picture receiver while realizing an audio-visual area necessary forregeneration of highly uniform acoustic characteristic in accordancewith the screen size of the picture receiver. The speaker system forpicture receiver of the present invention is useful as a monitor speakersystem for a screen projection type display, organic EL, and liquidcrystal display as well as a display using CRT or PDP. Also, it can beused as a monitor speaker system for shop front display.

1. A speaker system for picture receiver, comprising: a first speakerfor reproducing medium and high range sound which form a sound imagenearly at the vertical center in the right and left region of the screenof a picture receiver; and a second speaker for reproducing medium andlow range sound under the screen, wherein when a listening point is setat a point a first distance apart in forward direction of the screen andwithin a second distance from the front axis at the center of the rightand the left of the screen, distance R1 from the sound source positionof the first speaker to the listening point, distance R2 from the soundsource position of the second speaker to the listening point, andcrossover frequency f of the first speaker and the second speakerfrequency-divided by dividing network satisfy the following relativeformula:|exp(−j×k×R1)×exp(j×D×π/4)+(−1)^(D+1)×exp(−j×k×R2)×exp(−j×D×π/4)|≧1/√{squareroot over (2)},k=2π×f/c, exp=exponential function, j=unit of complex number, c=soundvelocity, π=circular constant, D=degree of dividing network (0 orpositive integers).
 2. The speaker system for picture receiver of claim1, wherein the second distance is 1 m, the crossover frequency f is 200Hz or over, and the second speaker satisfies the relative formula. 3.The speaker system for picture receiver of claim 1, wherein the firstdistance is three times the vertical size of the screen.
 4. The speakersystem for picture receiver of claim 1, wherein the crossover frequencyf is not lower than 400 Hz and not higher than 600 Hz.
 5. A speakerinstalling method of installing a speaker system for picture receivercomprising: a first speaker for reproducing medium and high range soundwhich form a sound image nearly at the vertical center in the right andleft region of the screen of a picture receiver, and a second speakerfor reproducing medium and low range sound under the screen, wherein thefirst speaker and the second speaker are installed in such place thatwhen a listening point is set at a point a first distance apart inforward direction of the screen and within a second distance from thefront axis at the center of the right and the left of the screen,distance R1 from the sound source position of the first speaker to thelistening point, distance R2 from the sound source position of thesecond speaker to the listening point, and crossover frequency f of thefirst speaker and the second speaker frequency-divided by dividingnetwork satisfy the following relative formula:|exp(−j×k×R1)×exp(j×D×π/4)+(−1)^(D+1)×exp(−j×k×R2)×exp(−j×D×π/4)|≧1/√{squareroot over (2)},k=2π×f/c, exp=exponential function, j=unit of complex number, c=soundvelocity, π=circular constant, D=degree of dividing network (0 orpositive integers).
 6. The speaker installing method of installing aspeaker system for picture receiver of claim 5, wherein the seconddistance is 1 m and the crossover frequency f is 200 Hz or over.
 7. Thespeaker installing method of installing a speaker system for picturereceiver of claim 5, wherein the first distance is three times thevertical size of the screen.
 8. The speaker installing method ofinstalling a speaker system for picture receiver of claim 5, wherein thecrossover frequency f is not lower than 400 Hz and not higher than 600Hz.